Generally, composites, such as artificial leather, in which nano fibers used as reinforcing materials are dispersed in matrix components have been prepared in such a manner that a nonwoven fabric is prepared from nano fibers, and then a solution with the matrix components dissolved in a solvent is impregnated or sprayed into the nonwoven fabric by an additional procedure.
However, the above conventional method requires an additional procedure of impregnating or spraying the matrix components into the nonwoven fabric, which makes the procedure complex and which have limitations in allowing the matrix components to be uniformly distributed between the nano fibers.
More specifically, the conventional method of preparing artificial leather, which is an example of composites, will be described. A composite fiber, made by conjugated-spinning the fiber forming component and the extracting component in a sea-island type or division type in order to make fibers ultrafine, is cut to prepare staple fibers, the staple fibers are laminated in the form of a web and needle-punched to prepare a nonwoven fabric, a polyurethane solution dissolved in a solvent of dimethyl formamide or the like is impregnated in the nonwoven fabric, and then the extracting component in the nonwoven fabric is dissolved out by treating the nonwoven fabric with a solvent such as caustic soda, thereby preparing artificial leather.
The above conventional method of preparing artificial leather has problems like a small contact are between the fibers and the matrix components (polyurethane) because the procedure is not continuous and it is difficult to make the diameter of the fibers 1 micrometer or less.
As another method of preparing a fiber reinforced composite, U.S. Pat. No. 4,511,663 suggests a method of dispersing carbon fibers coated with a metal in matrix components of glass or glass-ceramics or the like by a reinforcing material.
Additionally, U.S. Pat. No. 5,725,710 suggests a method in which a continuous filament is passed through a solution with thermoplastic powder dispersed in water, the water is removed, and the thermoplastic powder is melted onto the continuous filament. U.S. Pat. No. 6,818,288 suggests a method of positioning layers of woven fiber fabric in matrix components, such as carbon, by reinforcing material.
However, the above conventional methods are not continuous, and the composites are not reinforced with nano fibers, thus the contact area between the matrix components and the reinforcing material is small, thereby deteriorating the physical properties such as resistance to deformation.
To solve the conventional problems, it is an object of the present invention to prepare by a continuous and simple procedure a composite which is superior in physical properties due to a large contact area between matrix components and reinforcing material (nano fibers).